Office 365 (Web) - Folders List / Creating a Folder
An overview of the Folders list in Outlook 365
The Folders list shows the default folders that are created for all mailboxes and any folder that you create.
You can select Expand to show the Folders list, or select Collapse to hide it. Select any folder in the list to view its contents.
You can right-click any item in the Folders list to see a menu of things you can do, such as create a new folder, delete an existing folder, or empty a folder. On a touch screen, tap and hold an item to the menu for that item.
Create a new folder
1. Right-click (or tap and hold) any folder in the Folders list and choose create new folder. A new, unnamed, folder is added as a subfolder to the folder you selected.
To create a folder that's not a subfolder, right-click (or tap and hold) your name above your Inbox folder.
2. Type a name for the new folder, and then press Enter.